Blower motor non funcitonal

[NocturnalEmber]

Hey there everyone,

While I finally seemed to have gotten my starting/running issue solved (thanks to the immense contributions to those involved!), my remaining issues I have split into three separate threads, with this one focusing on the blower motor.

What I've done so far:

*Replaced all fuses and verified connection between the fuses, no fuses are blowing.

The switch for the fan speed does not work on *Any* setting. I figured it would be like my old RX-7, where the highest setting just bypasses the resistor entirely and sends straight 12V to the motor, so it would at least work on the highest setting, but alas, it does not.

During my past diags, I believe I've verified that there is current going through the fuse box in the passengers kick panel through the AC fuse.

 

[NocturnalEmber]

I was looking through the FSM, and I had a question I was hoping someone could clarify for me, it says to ground out one of the wires leading to the blower motor switch in the testing procedure.

Does that mean I disconnect the harness plug and ground the chosen wire on the Switch side of the plug, or on the side connected to the car's harness?    It says going to the switch, but I just wanted to make sure I didn't have to disconnect or ground a specific side.

Edited November 13, 2023 by NocturnalEmber

[jfa.series1]

There are two wires coming from the motor that are connected to the harness going to the switch. Disconnect the harness wires from the motor wires. Ground one of the motor wires and apply a 12V power source to the other wire. Listen for the blower motor to respond. If it works then your problem is elsewhere.

[SteveJ]

Well, for whatever reason, my response from this weekend didn't post, but thanks to the software at this site, it wasn't gone forever.

Let's look at the circuit for the fan. This is for the 240Z, so it doesn't show the ignition relay, but this is close enough for testing purposes. Also, this assumes you don't have factory AC in your car. The easy way to tell is that the factory AC cars had a 4 speed switch. (You have factory AC per another thread.)

So, there is a 2 pin connector on the fan motor. Unplug it.

With the key in ACC or ON, you should see voltage to ground at the red wire on that connector. Test for that and report your results.

If you do see voltage to ground, you can turn the key to OFF. Now we will focus on the black wire on the connector.

1. Put the fan switch on high.
2. Measure resistance to ground on the black wire and record your results.
3. Put the switch on medium.
4. Measure resistance to ground on the black wire and record your results.
5. Put the switch on low.
6. Measure resistance to ground on the black wire and record your results. (Are you noticing the pattern, yet?)

Report your results so we can see what to diagnose next.